Generating set preloader

Abstract

An diesel or gas engine-generator unit comprises an internal combustion engine and an alternator, the output of which unit, in use, is adapted to supply electrical power to a site load. The unit is further provided with means to apply a further load ( 2 ) to the unit controllable by a switching arrangement ( 4,5 ), the unit further comprising a controller, which can be the genset controller, which is adapted to control the switching unit to apply the further load ( 2 ) before electrical power is supplied to the site load. This preloading of the generator enables significantly greater load steps to be applied to the genset. The preload can be a resistive, capacitive or inductive load and can also be applied in steps.

The invention claimed is: 
     
       1. An internal combustion engine-generator unit comprising an internal combustion engine and an alternator, wherein the output of the internal combustion engine-generator unit, in use, is adapted to supply electrical power to a site load, the supply of electrical power being controllable by a switching arrangement, such that application of electrical power to the site load generates a current inrush that corresponds to a power surge commonly referred to as a load step,
 characterised in that the internal combustion engine-generator unit is further provided with means to apply a preload to the internal combustion engine-generator unit controllable by the switching arrangement, wherein the preload is a resistive load comprising a set of one or more resistors, the resistive load being adapted to the characteristics of the site load, and the internal combustion engine-generator unit further comprising a controller adapted to control the switching arrangement to apply the preload before electrical power is supplied to the site load, whereby application of the preload is adapted to reduce distortions in the output of the internal combustion engine-generator unit due to the load step, 
 characterised in that, in use, the switching arrangement breaks the connection to the preload before closing the connection to the site load. 
 
     
     
       2. The internal combustion engine-generator unit according to  claim 1 , characterised in that the preload comprises a plurality of loads, and the switching arrangement comprises a switching arrangement for each of the plurality of loads, wherein the individual application of which loads is controllable by the controller so that, in use, the preload can be increased or decreased in stages. 
     
     
       3. The internal combustion engine-generator unit according to  claim 1 , characterised in that the preload can be applied to the internal combustion engine-generator unit in stages and/or progressively. 
     
     
       4. The internal combustion engine-generator unit according to  claim 3 , characterised in that the preload comprises a plurality of loads, and the switching arrangement comprises a switching arrangement for each of the plurality of loads, wherein the individual application of which loads is controllable by the controller so that, in use, the applied preload can be increased or decreased in stages. 
     
     
       5. An internal combustion engine-generator unit comprising an internal combustion engine and an alternator, wherein the output of the internal combustion engine-generator unit, in use, is adapted to supply electrical power to a site load, the supply of electrical power being controllable by a switching arrangement, such that application of electrical power to the site load generates a current inrush that corresponds to a power surge commonly referred to as a load step,
 characterised in that the internal combustion engine-generator unit is further provided with means to apply a preload to the internal combustion engine-generator unit controllable by a first switch of the switching arrangement, wherein the preload is a resistive load comprising a set of one or more resistors, the resistive load being adapted to the characteristics of the site load, and the internal combustion engine-generator unit further comprising a controller adapted to control the first switch of the switching arrangement to apply the preload before electrical power is supplied to the site load by a second switch of the switching arrangement, whereby application of the preload is adapted to reduce distortions in the output of the internal combustion engine-generator unit due to the load step, 
 characterised in that, in use, the switching arrangement causes the first switch and the second switch to be closed at the same time for a predetermined time period, before the first switch is opened to break the connection to the preload, while the second switch remains closed.